1. Field of Invention
The present invention relates to a method for manufacturing solar cells. More particularly, the present invention relates to a method for forming solar cells having textured structures.
2. Description of Related Art
Solar energy has gained many research attentions for being a seemingly inexhaustible energy source. Solar cells are devices developed for such purpose by converting solar energy directly into electrical energy.
Currently, solar cells are often made of single crystalline silicon, poly crystalline silicon, or amorphous silicon. In 2005, a solar cell with a high efficiency of 24.7% is developed, which is Passivated Emitter with Rear Locally Diffused (PERLD) Solar Cell. In PERLD solar cell, a pyramid-like structure is formed on the surface of the transparent conductive layer for trapping an incident light in the solar cell. Also, a high quality silicon wafer is employed in the solar cell. However, production of these types of solar cells would require not only high quality silicon wafers but also complicated processes, thereby rendering the manufacturing process cost in-effective.
For improving the above mentioned problem, a textured glass substrate formed by a sandblasting process is reported. Unfortunately, all the textured glass substrates formed by sandblasting processes substantially have different textured structures. That is, the textured structure formed on one glass substrate differs from another glass substrate. Thus, quality control, particularly, the reproducibility of the textured glass, during mass production may not be easily achieved.
Recently, a textured transparent conductive oxide (TCO) in solar cells is developed. One example is by depositing a textured layer of fluorine doped tin dioxide (SnO2:F). The fluorine doped tin dioxide may form a desired crystalline surface, which has a columnar or pyramidal texture when deposited at a temperature of about 500 to 600° C. However, the requirement of high temperature makes the manufacturing process cost in-effective.
Therefore, there exists in this art a need of an improved method, which would resolve the above mentioned problem.